Scramupx

Overview

Executive Summary

Infection Vector and Technical Capabilities

• UPX Evasion: UPX is a legitimate compression tool, and most AV engines have built-in routines to automatically decompress UPX files for scanning. ScramUPX modifies the UPX "magic numbers," section names, and the decompression stub within the executable.
• Anti-Analysis: When an AV engine encounters the scrambled file, its automated UPX unpacker fails because the expected structure is invalid. The AV is then forced to scan only the scrambled, compressed data, which rarely matches known malware signatures.
• Execution: Despite the scrambled headers, the threat actor ensures the modified executable still contains a functional, albeit non-standard, unpacking stub that allows the payload to successfully execute and decompress itself in memory when run by the victim.

Threat Assessment

Incident Response and Remediation

• Immediate Isolation and Triage: Isolate the endpoint. Do not attempt to run the file to see what it does.
• Dynamic Analysis (Sandboxing): The only effective way to determine the true nature of a ScramUPX-packed file is to execute it in a secure, isolated malware sandbox (e.g., Cuckoo Sandbox) and observe its behavioral telemetry (network connections, process injection).
• Memory Forensics: If the file has already been executed, traditional file scanning is useless. Incident responders must capture the system's RAM and perform memory forensics to extract the uncompressed malicious payload that is currently running in memory.

Known aliases

Threat reports may refer to this family under multiple names:

• Packer.ScramUPX
• Tool.UPXScrambler
• Obfuscator.Win32

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1059.001: Restrict execution of PowerShell. Enforce PowerShell Constrained Language Mode and Script Block Logging.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_SCRAMUPX_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Scramupx"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "scramupx" ascii wide nocase
        $s2 = "packer.scramupx" ascii wide nocase
        $s3 = "tool.upxscrambler" ascii wide nocase
        $s4 = "obfuscator.win32" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Scramupx (Advanced Threat) Execution & Triage
id: 4f514215-3e8c-502f-99ed-17bc4bb372c9
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Scramupx malware family. Detects proxy execution, reflective DLL loading,
  and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/scramupx
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.advanced-threat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1027_002
- attack.t1562_001
- attack.t1059_001
- attack.t1055
- attack.t1071_001
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \powershell.exe
    - \cmd.exe
    - \rundll32.exe
    - \regsvr32.exe
    CommandLine|contains:
    - DownloadString
    - IEX(
    - '/s /n /u /i:'
    - sc create
    - start-process
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_SCRAMUPX_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Scramupx tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "scramupx" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Enforce forensic network isolation on all suspected endpoints while maintaining an out-of-band telemetry conduit to capture live Scramupx adversary activity.
2. Perform full memory dumps across identified staging nodes to extract memory-only implants, kernel rootkit hooks, and decrypted Scramupx C2 infrastructure IP/domain lists.
3. Review Active Directory domain controller authentication logs for anomalous Kerberos ticket requests (Pass-the-Ticket, Golden Ticket) and unauthorized DCSync operations associated with Scramupx.
4. Block all confirmed C2 domains, dynamic DNS endpoints, and proxy IP addresses across perimeter firewalls, proxies, and DNS security gateways.
5. Conduct an enterprise-wide sweep across surrounding subnets for secondary webshells, WMI event subscriptions, or remote execution tooling left behind by Scramupx operators.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not assume the incident is resolved simply because an antivirus tool removed the initial Scramupx dropper; always verify that secondary payloads and persistence hooks have been eradicated.
2. Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Scramupx until memory triage is complete.
3. Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.

References & External Analysis

• Search "scramupx" on VirusTotal (External Analysis)
• Search "scramupx" on Any.Run (Sandbox Sandbox)
• Search "scramupx" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Advanced Threat)

Explore other documented threats in the same operational category:

• Stalk
• Taterf
• Doubleagent
• Funmood
• Clickshell
• Coupons
• Wpepro
• Monitortool

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/scramupx.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.